Do quality teachers influence their peers as well as their students?

Teachers raise their games when the quality of their colleagues improves, according to a new studyRequires Adobe Acrobat Reader offering some of the first evidence to document a “spillover effect” in teaching.

Authors C. Kirabo Jackson and Elias Bruegmann based their findings on an analysis of 11 years of data on North Carolina schoolchildren. The study is due to be published in October in American Economics Journal: Applied Economics, a peer-reviewed journal.

“If it’s true that teachers are learning from their peers, and the effects are not small, then we want to make sure that any incentive system we put in place is going to be fostering that and not preventing it,” said Mr. Jackson, an assistant professor of labor economics at Cornell University in Ithaca, N.Y. “If you give the reward at the individual level, all of a sudden my peers are no longer my colleagues—they’re my competitors. If you give it at the school level, then you’re going to foster feelings of team membership, and that increases the incentive to work together and help each other out.”